Spark-plug.



A* J. MUMMERT.

SPARK PLUG.

APPLicATloN FILED JULY 12l 1915.

Patented Feb. 13, 1917.

Arden UNITED STATES PATENT OFFICE.

ABDEN J. MUMMERT, OF ST. LOUIS, MISSOURI, ASSIGNOR TO McQUAY-NORBIS MANU- FACTURING COMPANY, 0F ST.

LOUIS, MISSOURI, A CORPORATION OF MISSOURI.

SPARK-PLUG.

Application led July 12, 1915.

To all whom it may concern:

Be it known that I, ARDEN J. MUMM'ERT, a citizen of the United States, residing at St. Louis, State of Missouri, have invented certain new and useful Improvements in Spark-Plugs, of which the following is a full, clear, and exact description, reference being had to the accompanying drawings, forming a part hereof.

My invention has relation to improvements in spark-plugs; and it consists in the novel features of construction more fully set forth in the specification and pointed out in the claims.

The present improvement is directed to the construction of spark-plugs for explosive engines, and has for its object the construction of a plug in which the element ofexpansion due to overheating of the plug is eliminated, thereby avoiding the breaking or cracking of the plug while in service. As well understood in the art the insulating members or plugs of these spark-plugs are generally constructed of porcelain or equivalent material Which is liable to crack from the excessive heating of the same by reason of their contact with the burning gases in the engine cylinder. In the present embodiment of my invention I rovide the exposed portion of the plug wit suitable iins, ribs or equivalent heat-radiating formations which, by reason of their exposure to the atmosphere, permit a rapid cooling of the plug owing to their extended surface, and thus prevent that undue expansion in the plug from which cracking or breaking usually follows. The radiating formations or fins referred to, perform the further function of preventing the trickling of Water (if present) along the plug between the binding post and the metallic socket, or plug-holder, thereby eliminating the danger of short-circuiting the electric currents and destroying .the sparking efiiciency of the device. The cooling of the plug has still another advantage, to wit: It serves to maintain the temperature within the cylinder in the immediate vicinity of the plug below the point where lubricating or other oil (always present) can take fire, thereby preventing the accumulation of films of unconsumed carbon (resulting from the incomplete combustion of the oil) on the inner terminal of the plug, these films as well Specication of Letters Patent.

Patented Feb. 13, 1917.

Serial No. 39,359.

understood in the art being good electric conductors and thus tending to short-circuit the sparking terminals. The advantages of the invention will be fully apparent from a detailed description thereof in connection with the accompanying drawing in which Figure 1 represents an elevation of my improved spark plug applied to an engine cylinder, the latter being shown in longitudinal middle section; Fig. 2 is an enlarged middle longitudinal section of the spark plug; and Fig. 3 is a top pian of the same.

Referring to the drawings, B represents a battery, C a1 circuit breaker ofthe battery circuit, and D the transformer from which lead the wires fw, w', to the plug and enginey cylinder as well understood in the art and herein shown more or less convention-` ally and diagrammatically. The insulating member consists of a one-piece plug 1 of porcelain or equivalent material, the same being traversed axially by the electrode or electric terminal 2, the outer end of which is screw-threaded to receive a screw-cap 3 to which the wire w is anchored. The medial portion of the plug is received in a metallic socket 4 which is in turn screwed to the engine cylinder, the socket being formed with an inner annular shoulder s for the support of a gasket 5 against which the plug is shouldered, the upper edge of the socket being rolled or beaded over the shoulder s of the plug. The socket 4 has secured thereto the opposite electric terminal or electrode 2.

In the present embodiment of my inventio I form the plug with a series of parallel coo ing fins or heat radiating formations 6 spaced apart along planes transverse to 'the longitudinal axis of the plug, the fins being slightly undercut to prevent any water which may lodge on a fin from trickling along the iin down the wall of the plug 'to the next fin and thus forming a short-circuiting water film or conductor between the cap 3 and socket 4. It is apparent of course that were a continuous film of Water to form or accumulate on the plug between the members 3 and 4, it would result in short circuiting the terminals-2 and 2', and the sparking efficiency of the spark plug would be impaired or wholly destroyed. The fins 6 while preventing the formation of a conlli , the

tinuous hlm of water (it present) between the parts 3 and l thus avoiding the shortcircuiting of the spark terminals 2, 2', have another advantage, to wit. ey present extended heat radiating surfaces to the contact ot the atmosphere thereby cooling the plug and preventing undue expansion and contraction thereof as a result of material changes ot temperature, and hence prevent cracking or splitting of the plug. Furthermore, by keeping the plug cool, the temperature of' the engine gases in the immediate neighborhood. of the inner terminal of `the plug is maintained at a point below that at which accumulations of oil (particularly lubricating) in the cylinder will take fire, thereby preventing the accumulation on the plug of layers of unconsunied carbon indicated by the reference letter a (Fig. 2), which layers reaching as they ordinarily do from the socket l to the terminal 2 have the ellect of short-circuiting the terminal 2 and thus destroying the sparking function of device.

lt will thus be seen from the foregoing that the cooling tins 6 or their equivalents not only keep the plug cool thereby prevent ing cracking or splitting of the plug, but they serve to prevent formations of shortcircuiting Water ilms on the outside of the plug, and of short-circuiting carbon layers on the plug inside the cylinder. As best seen from l ig. 2, the ns overhang the socket fl, thereby protecting the joint at the shoulder e against possible lodgment of water. ln lieu of annular tins or ribs as here shown l may substitute other equivalent cooling formations without a'ecting the nature or spirit of my invention. ll may likewise adopt other t'orins ot plug from that here shown.

antenne Having described .my invention what l claim is:

l. ln combination with a socket provided with an inner shoulder, a one-piece insulating member or plug inserted into the socket and having a medial portion resting on said shoulder, an inner terminal extending inwardly beyond the shoulder, and an-outer terminal projecting outside the socket, Said outer terminal being provided with a series of peripheral ribs overhanging the socket and disposed in planes transverse to the axis of the plug.

2. ln combination with a socket provided with an inner shoulder, a one-piece insulating member or plug inserted into the socket and hav-ing a medial portion resting on said shoulder, an inner terminal extending -inwardly beyond the shoulder and an outer portion projecting outside the socket, said outer portion being formed with radiating peripheral ribs overhanging the socket and disposed in planes transverse to the axis of the plug and spaced apart, 'and proportioned to maintain the temperature of the plug at a temperature sufficiently low to prevent undue expansion and consequent cracking of the plug.

3. ln combination with' a socket, a onepiece insulating member or plug inserted into the socket, said plug having a ribbed portion projecting outside the socket, the ribs being disposed in planes transverse to the axis ot the plug, and overhanging the socket.

ln testimony whereof l alix my in presence of two wltnesses.

Annen J. MuMMERT.'

signature,

Witnesses:

Ervin S'rnnnx, llnsn M2 SIEGEL. 

